About Kino no Tabi

I recently read the first volume of "Kino no Tabi: The Beautiful World" and went to YouTube to see if I could find the anime episodes. I watched the short movie "Kino's Journey: Life Goes On" and I wonder, what is the significance of Kino cutting her hair short and then referring to herself in masculine terms when talking about her hair?

If you haven't seen it, you can see what I am referring to here:

Her teacher sends her off and she is forced to kill the woman she goes to see - presumably the first time she has had to kill. After she kills the woman, she cuts her hair short and returns to her teacher. Her teacher says that she likes the way she cut her hair, to which Kino replies, "Yes, I like it as well" using the masculine form of "I". What is the significance of these actions?